In order to observe a very small area on an object, a scanning electron microscope (SEM), transmission electron microscope (TEM) or the like is used. Generally, in these apparatuses, a chassis for arranging a specimen is vacuum-pumped to turn the specimen atmosphere into a vacuum state, and an image of the specimen is picked up. Since electron beams are scattered by gas molecules in the atmosphere or the like, it used to be considered preferable that the passage of electron beams is a vacuum. However, biological/chemical specimens, liquid specimens and the like are damaged or changed in state by a vacuum. Meanwhile, there has been a great need for observation of such specimens with an electron microscope and SEM apparatuses which enable observation of an observation target specimen under atmospheric pressure have been developed recently.
PTL 1 discloses a SEM apparatus which enables observation under atmospheric pressure. In this apparatus, in principle, an isolation film capable of transmitting electron beams is provided between an electron optical system and a specimen, thus separating a vacuum state and an atmospheric state from each other. This is different from an observation method for an environmental cell or the like, in that the specimen is brought near the isolation film and observed in a non-contact state. This method enables observation by maintaining the passage immediately before electron beams reach the isolation film, in a high vacuum state by the isolation film, thus preventing the electron beams from being scattered, and also by limiting the area where the scattering of electron beams occurs to a very short distance between the isolation film and the specimen.
Meanwhile, NPL 1 discloses a method of processing a diamond by casting electron beams in a low vacuum atmosphere. NPL 1 also mentions a method of removing nanopillars on a diamond substrate.